Enchantment, 2G (3) Whenever a creature with power 5 or greater comes into play under your control, you may put two +1/+1 counters on it. Why settle for mere enormity?
Illus. Steve Prescott
10/1/2008: The ability checks that creature's power only once: when that creature comes into play. The trigger checks a creature's initial power upon being put in play, so it will take into account counters that it comes into play with and static abilities that may give it a continuous power boost once it's in play (such as the one on Glorious Anthem). After the creature is already in play, boosting its power with a spell (such as Giant Growth), activated ability, or triggered ability won't allow this ability to trigger; it's too late by then. Once the ability triggers, it will resolve no matter what the creature's power may become while the ability is on the stack.